Conus ebraeus

Abstract: Information on genetic connectivity and struc- ture of populations in the tropical Pacific is critical for making inferences about the origins and maintenance of diversity in this region. Sequences of the mitochondrial COI gene from 92 individuals of the trans-Pacific gastropod Conus ebraeus from eight localities spanning the tropical Pacific were analyzed to determine whether populations in the western, central, and eastern Pacific exhibit genetic structure, to examine the demographic histories of popula- tions, and to infer patterns of gene flow. A total of 43 unique haplotypes were recovered, including a common haplotype that occurred in six of the eight populations examined. AMOVA and pairwise F-statistics showed that populations in the western and central Pacific were significantly dif- ferentiated from populations in the eastern Pacific, but no other evidence of structure. Bayesian isolation-migration (IM) analysis suggested that populations in the western and central Pacific separated from those in eastern Pacific dur- ing the Pleistocene. Examination of mismatch distributions and results from IM revealed that populations in the western and central Pacific expanded during the Pleistocene. Gene flow across the East Pacific Barrier appears to occur pre- dominantly westward.

Abstract: Anomalous mitochondrial and nuclear gene sequences in individuals of the widely distributed tropical marine gastropod Conus ebraeus that were not distinguishable by shell shape and color pattern characters suggested the presence of a second, cryptic species. We tested this hypothesis by genetic, morphological, and ecological comparisons of additional individuals from the site in Okinawa where the two forms co-occurred. Radular tooth size and shape, prey type in nature, and microhabitats utilized differed markedly between the two forms. Adults with typical C. ebraeus DNA and radular teeth preyed primarily on errant polychaetes (Eunicidae); those with anomalous DNA and teeth ate mainly sedentary capitellids. Juveniles (shell length <13 mm) had more similar teeth and ate primarily syllids. Radular teeth of the anomalous form agreed with those of Conus judaeus, distinguished from C. ebraeus by Rudolph Bergh in 1895 solely on tooth characters of one specimen from the Philippines. Samples from other widely scat...

Abstract: Venomous organisms serve as wonderful systems to study the evolution and expression of genes that are directly associated with prey capture. To evaluate the relationship between venom gene expression and prey utilization, we examined these features among individuals of different ages of the venomous, worm-eating marine snail Conus ebraeus. We determined expression levels of six genes that encode venom components, used a DNA-based approach to evaluate the identity of prey items, and compared patterns of venom gene expression and dietary specialization. C. ebraeus exhibits two major shifts in diet with age—an initial transition from a relatively broad dietary breadth to a narrower one and then a return to a broader diet. Venom gene expression patterns also change with growth. All six venom genes are up-regulated in small individuals, down-regulated in medium-sized individuals, and then either up-regulated or continued to be down-regulated in members of the largest size class. Venom gene expression is not significantly different among individuals consuming different types of prey, but instead is coupled and slightly delayed with shifts in prey diversity. These results imply that changes in gene expression contribute to intraspecific variation of venom composition and that gene expression patterns respond to changes in the diversity of food resources during different growth stages.